Peptidyl compounds and their therapeutic use

ABSTRACT

Tripeptidyl derivatives having a SH or acylS group and which are amides, have therapeutic utility via MMP or TNF inhibition.

FIELD OF THE INVENTION

This invention relates to a novel class of peptidyl derivatives, to processes for their preparation, and to their use in medicine.

BACKGROUND TO THE INVENTION

Tumour Necrosis Factor (TNF) is a cytokine which is produced initially as a cell-associated 28 kD precursor. It is released as an active, 17 kD form (D-M Jue et al, (1990) Biochemistry, 29:8371-8377), which can mediate a large number of deleterious effects in vivo. When administered to animals or humans it causes inflammation, fever, cardiovascular effects, haemorrhage, coagulation and acute phase responses, similar to those seen during acute infections and shock states. Chronic administration can also cause cachexia and anorexia. Accumulation of excessive TNF can be lethal.

There is considerable evidence from animal model studies that blocking the effects of TNF with specific antibodies can be beneficial in acute infections, shock states, graft versus host reactions and autoimmune disease. TNF is also an autocrine growth factor for some myelomas and lymphomas and can act to inhibit normal heamatopoiesis in patients with these tumours.

Preventing the production or action of TNF is, therefore, predicted to be a potent therapeutic strategy for many inflammatory, infectious, immunological or malignant diseases. These include, but are not restricted to, septic shock, haemodynamic shock and sepsis syndrome (Mathison et al, (1988) J. Clin. Invest. 81:1925-1937; Miethke et al (1992), J. Exp. Med. 175:91-98), post ischaemic reperfusion injury, malaria (Grau et al (1989), Immunol. Rev. 112:49-70); mycobacterial infection (Barnes et al (1992) Infect. Imm. 60:1441-6), meningitis, psoriasis, congestive heart failure, fibrotic disease, cachexia, graft rejection, cancer, autoimmune disease, rheumatoid arthritis, multiple sclerosis, radiation damage, toxicity following administration of immunosuppressive monoclonal antibodies such as OKT3 or CAMPATH-1 and hyperoxic alveolar injury.

Current clinical anti-TNF strategies involve the use of corticosteroids such as dexamethasone, and the use of cyclosporin-A or FK506, which are non-specific inhibitors of cytokine gene transcription. Phosphodiesterase inhibitors such as pentoxyfilline have been shown to be more specific inhibitors of TNF gene transcription (Endres S. (1991) Immunol. 72:56-60, Schandene et al (1992), Immunol. 76:30-34, Alegre M L, et al (1991); Transplantation 52:674-679, Bianco et al (1991) Blood 78:1205-1221). Thalidomide has also been shown to inhibit TNF production by leucocytes (Sampajo et al (1991), J. Exp. Med. 173:699-703). In experimental settings, anti-TNF monoclonal antibodies, soluble TNF receptors and soluble TNF receptor/immunoadhesins have been shown to specifically inhibit the effects of TNF action (Bagby et al (1991) J. Infect. Dis. 163:83-88, Charpentier et al. (1991) Presse-med. 20:2009-2011, Silva et al (1990) J. Infect. Dis. 162:421-427; Franks et al (1991) Infect. Immun. 59:2609-2614, Tracey et al (1987) Nature 330:662-664; Fischer et al (1992) PNAS USA in press, Lesslauer et al (1991) Eur. J. Immunol. 21:2883-2886, Ashkenazi et al (1991) PNAS USA 88:10535-10539).

It has recently been shown that the effects of TNF are mediated by two peptides, TNFα and TNFβ. Although these peptides have only 30% homology with each other, they activate the same receptors and are encoded by immediately adjacent genes. As used herein, the term tumour necrosis factor or TNF therefore means tumour necrosis factor α and peptides having a high degrees of sequence homology with, or substantially similar physiological effects to, TNF α, for example TNF β.

One of the objectives of the present invention is to provide compounds which substantially inhibit the release of TNF from cells, and therefore may be used in the treatment of conditions mediated by TNF. Such uses include, but are not limited to, the treatment of inflammation , fever, cardiovascular effects, haemorrhage, coagulation and acute phase response, cachexia and anorexia, acute infections, shock states, graft versus host reactions and autoimmune disease.

In normal tissues, cellular connective tissue synthesis is offset by extracellular matrix degradation, the two opposing effects existing in dynamic equilibrium. Degradation of the matrix is brought about by the action of proteinases released from resident connective tissue cells and invading inflammatory cells, and is due, in part, to the activity of at least four groups of metalloproteinases. These are the collagenases (interstitial collagenase, MMP-1; PMN collagenase, MMP-8, collagenase-3, MMP-13), the gelatinases (gelatinase A, MMP-2, 72 kDa-gelatinase, Type IV collagenase; gelatinase B, MMP-9, 92 kDa-gelatinase, Type IV collagenase) the stromelysins (proteoglycanase, MMP-3, stromelysin-1, transin; stromelysin-2, MMP-10; stromelysin 3, MMP-11) and the membrane type matrix metalloproteinases (MT-1, MMP-14; MT-2, MMP-15; MT-3, MMP-16 and MT-4, MMP-17). Normally these catabolic enzymes are tightly regulated at the level of their synthesis and secretion and also at the level of their extracellular activity, the latter through the action of specific inhibitors, such as TIMP (tissue inhibitors of metalloproteinase), which form inactive complexes with metalloproteinases, and more general proteinase inhibitors such as α₂ -macroglobulins.

The accelerated, uncontrolled breakdown of connective tissues by metalloproteinase catalysed resorption of the extracellular matrix is a feature of many pathological conditions such as rheumatoid arthritis, osteoarthritis, septic arthritis, corneal, epidermal or gastric ulceration; tumour metastasis or invasion; periodontal disease, proteinuria, coronary thrombosis associated with atherosclerotic plaque rupture and bone disease. The inhibitors claimed herein may also be useful in preventing the pathological squaelae following a traumatic injury that could lead to a permanent disability. These compounds may also have utility as a means for birth control by preventing ovulation or implantation. It can be expected that the pathogenesis of such diseases is likely to be modified in a beneficial manner by the administration of metalloproteinase inhibitors and numerous compounds have been suggested for this purpose [for a general review see R C Wahl, et al Ann. Rep, Med. Chem. 25, 175-184, Academic Press Inc., San Diego (1990)].

A number of small peptide like compounds which inhibit metalloproteinases have been described. Perhaps the most notable of these are those relating to angiotensin converting enzyme (ACE) where such agents act to block the conversion of the decapeptide angiotensin I to angiotensin II, a potent pressor substance. Compounds of this type are described in EP-A-0012401. Also, related mercaptoamide peptidyl derivatives have shown ACE inhibitor activity in vitro and in vivo (H N Weller et al (1984), Biochem Biophys. Res. Comm., 125(1):82-89).

Compounds which have the property of inhibiting the action of metalloproteinases involved in connective tissue breakdown such as collagenase, stromelysin and gelatinase have been shown to inhibit the release of TNF both in vitro and in vivo (A J H Gearing et al (1994), Nature, 370:555-557; G M McGeehan at al (1994), Nature, 370:558-561: M J Crimmin et al, WO 93/20047 and WO 94/10990). All of these reported inhibitors contain a hydroxamic acid zinc binding group.

It is, therefore, a further objective of this invention to provide compounds which, in addition to inhibiting TNF release, also may inhibit the action of certain MMPs, and hence may be used in the treatment of patients who suffer from condition mediated by TNF and/or MMPs such uses include, but are not limited to inflammation, fever, cardiovascular effects, haemorrhage, coagulation and acute phase response, cachexia and anorexia, acute infections, shock states, graft versus host reactions and autoimmune disease; and those involving tissue breakdown such as bone resportion, inflammatory diseases, dermatological conditions, tumour growth, angiogenesis and invasion by secondary metastases, in particular rheumatoid arthritis, osteoarthritis, periodontitis, gingivitis, corneal ulceration, tumour growth, angiogenesis and invasion by secondary metastases.

Compounds that inhibit collagenase, which possess structural portions akin to those of the instant invention include those encompassed by U.S. Pat. No. 4,511,504 issued Apr. 16, 1985; U.S. Pat. No. 4,568,666, issued Feb. 4, 1986.

Compounds of related structure that are claimed to inhibit stromelysin (proteoglycanase) are encompassed by U.S. Pat. No. 4,771,037, issued Sep. 13, 1988.

The applicants believe that stromelysin and collagenase inhibitors have utility in preventing articular cartilage damage associated with septic arthritis. Bacterial infections of the joints can elicit an inflammatory response that may then be perpetuated beyond what is needed for removal of the infective agent resulting in permanent damage to structural components. Bacterial agents have been used in animal models to elicit an arthritic response with the appearance of proteolytic activities. See J. P. Case et al (1989), J. Clin. Invest., 84:1731-40; R. J. Williams at al (1990), Arth. Rheum., 33: 533-41.

The applicants also believe that inhibitors of stromelysin, collagenase and gelatinase will be useful to control tumour metastasis, optionally in combination with current chemotherapy and/or radiation. See L. M. Matrisian et al (1986), Proc. Natl. Acad. Sci., USA, 83:9413-7; S. M. Wilhelm et al (1987), Ibid. 84:6725-29; Z. Werb et al (1989), J. Cell Biol., 109:872-889; L. A. Liotta et al (1983), Lab. Invest., 49:636-649; R. Reich et al in Metatasis; Ciba Foundation Symposium, Wiley, Chicester, 1988, pp. 193-210.

Secreted proteinases such as stromelysin, collagenase and gelatinase play an important role in processes involved in the movement of cells during metastatic tumour invasion. Indeed, there is also evidence that the matrix metalloproteinases are over expressed in certain metastatic tumour cell lines. In this context, the enzyme functions to penetrate underlying basement membranes and allow the tumour cell to escape from the site of primary tumour formation and enter the circulation. After adhering to blood vessel walls, the tumour cells use these same metalloproteinases to pierce underlying basement membranes and penetrate other tissues, thereby leading to tumour metastasis. Inhibition of this process would prevent metastasis and improve the efficacy of current treatments with chemotherapeutics and/or radiation.

These inhibitors should also be useful for controlling periodontal diseases, such as gingivitis. Both collagenase and stromelysin activities have been isolated from fibroblasts derived from inflamed gingiva (V. J. Uitto et al (1981), J. Periodontal Res., 16:417-424). Enzyme levels have been correlated to the severity of gum disease; C. M. Overall et al (1987), J. Periodontal Res., 22:81-88.

Proteolytic processes have also been observed in the ulceration of the cornea following alkali burns (S. I. Brown et al (1969), Arch. Opthalmol., 81:370-373). Mercapto-containing peptides do inhibit the collagenase isolated from alkali-burned rabbit cornea (F. R. Burns et al (1989), Invest. Opthalmol, 30:1569-1575). Treatment of alkali-burned eyes or eyes exhibiting corneal ulceration as a result of infection with inhibitors of these metalloendoproteinases in combination with sodium citrate or sodium ascorbate and/or antimicrobials may be effective in preventing developing corneal degradation.

Stromelysin has been implicated in the degradation of structural components of the glomerular basement membrane (GBM) of the kidney, the major function of which is to restrict passage of plasma proteins into the urine (W. H. Baricos et al (1989), Biochem. J., 254:609-612). Proteinuria, a result of glomerular disease, is excess protein in the urine caused by increased permeability of the GBM to plasma proteins. The underlying causes of the increased GBM permeability are unknown, but proteinases including stromelysin may play an important role in glomerular diseases. Inhibition of this enzyme may alleviate the proteinura associated with kidney malfunction.

It is suggested that inhibition of matrix metalloproteinase activity may prevent the rupturing of atherosclerotic plaques leading to coronary thrombosis. The tearing or rupture of atherosclerotic plaques is the most common event initiating coronary thrombosis. Destabilisation and degradation of the connective tissue matrix surrounding theses plaques by proteolytic enzymes or cytokines released by infiltrating inflammatory cells has been proposed as a cause of plaque fissuring. Such tearing of these plaques can cause an acute thrombolytic event as blood rapidly flows out of the blood vessel. High levels of stromelysin RNA message have been found to be localised to individual cells in atherosclerotic plaques removed from heart transplant patients at the time of surgery (A. M. Henney et al (1991), Proc. Nat'l. Acad. Sci. USA, 88:8154-8158). Inhibition of matrix metalloproteinases by these compounds may aid in preventing or delaying the degradation of the connective tissue matrix that stabilises the atherosclerotic plaques, thereby preventing events leading to acute coronary thrombosis.

It has been recently shown in a model of congestive heart failure (CHF) in the pig, that during CHF the are marked changes in the morphological structure of the heart. Ventricular dilation and wall thinning caused by changes to the extracellular matrix results in fewer collagen connections between cardiomyocytes and less total collagen. In such an instance a weaker force of contraction leads to an inefficient ventricular operation. It is believed that specific inhibitors of matrix metalloproteinases will play a key role in stabilising the extracellular matrix and therefore be important in the treatment and/or prevention of CHF.

It has recently been shown (WO 96/0240) that inhibitors of the matrix metalloproteinases, such as collagenase and stromelysin also inhibit the formation of human soluble CD23. CD23 is a 45 kDa type II integral protein expressed on the surface of a variety of mature cells, including B and T lymphocytes, macrophages, NK cells, Langerhans cells, monocytes, eosinophils and platelets (Delespesse et al, Adv. Immunology, 49, 1991, 149; Grangette et al, J., Immunol, 143, 1989, 3580). Several activities have been ascribed to soluble CD23 in man, all of which involve IgE regulation. Particular activities include:

i) antigen presentation

ii) IgE mediated eosinophil cytotoxicity

iii) B cell homing to lymph nodes and the spleen

iv) downregulation of IgE synthesis

Thus, overall the excessive production of soluble CD23 has been implicated in the overproduction of IgE, the hallmark of allergic diseases such as extrinsic asthma, rhinitis, allergic conjunctivitis, eczema, atopic dermatitis and anaphylaxis (Sutton et al, Nature, 366, 1993, 421). Elevated levels of soluble CD23 have also been observed in the serum of patients with chronic B lymphocytic leukaemia (Safarti et al, Blood, 71, 1988, 94), and in synovial fluid of patients with rheumatoid arthritis (Chomarat et al, Arthritis and Rheumatism, 36, 1993, 234).

It is therefore, a further objective of the present invention to provide compounds which inhibit the formation of human soluble CD23 for the production of a medicament for the treatment or prophylaxis of disorders such as allergy and autoimmune disease in which the overproduction of soluble CD23 is implicated, such as those described above.

Recent reports suggest that new enzymes of the MMP family also mediate the shedding of adhesion molecules such as the selectins, such as L-selectin. These soluble adhesion molecules are implicated in a number of diseases including cancer, autoimmunity and in the inflammatory response. It has been proposed that once cleaved, the selectin bind to particular ligands and this accounts for their biological activity. Thus, drugs that interfere with or prevent binding of the ligands to the selectins will be useful medicaments for treating a variety of the diseases described above. Therefore, it is a yet further objective of the present invention to provide compounds which inhibit the shedding of certain adhesion molecules and thus provide the production of a medicament for the treatment or prophylaxis of disorders such as cancer, autoimmune diseases or inflammatory diseases (such as inflammatory bowel disease and multiple sclerosis).

It is also believed that specific inhibitors of stromelysin and collagenase should be useful as birth control agents. There is evidence that expression of metalloproteinases, including stromelysin and collagenase, is observed in unfertilised eggs and zygotes and at further cleavage stages and increased at the blastocyst stage of fetal development and with endoderm differentiation (C. A. Brenner et al (1989), Genes & Develop., 3:848-59). By analogy to tumour invasion, a blastocyst may express metalloproteinases in order to penetrate the extracellular matrix of the uterine wall during implantation. Inhibition of stromelysin and collagenase during these early development processes should presumably prevent normal embryonic development and/or implantation in the uterus. Such intervention would constitute a novel method of birth control. In addition there is evidence that collagenase is important in ovulation processes. In this example, a covering of collagen over the apical region of the follicle must be penetrated in order for the ovum to escape. Collagenase has been detected during this process and an inhibitor has been shown to be effective in preventing ovulation (J. F. Woessner et al (1989), Steroids, 54:491-499). There may also be a role for stromelysin activity during ovulation (C. K. L. Too et al (1984), Endocrin., 115:1043-1050).

Collagenolytic and stromelysin activity have also been observed in dystrophic epidermolysis bullosa (A. Kronberger et al (1982), J. Invest. Dermatol., 79:208-211; D. Sawamura et al (1991), Biochem. Biophys. Res. Commun., 184:1003-8). Inhibition of metalloendoproteinases should limit the rapid destruction of connective components of the skin.

In addition to extracellular matrix comprising structural components, stromelysin can degrade other in vivo substrates including the inhibitors a₁ -proteinase inhibitor and may therefore influence the activities of other proteinases such as elastase (P. G. Winyard et al (1991), FEBS Letts., 279,1:91-94). Inhibition of the matrix metalloendoproteinases may potentiate the antiproteinase activity of these endogenous inhibitors.

From recent publications it is evident that several new enzymes of the MMP family have been identified, some of which may be important in disease. Collagenase 3, an enzyme found in breast carcinoma tissue may have utility in breast cancer (J M P Freije et al (1994), J. Biol. Chem., 269 (24); 16766-16773) and other disease states, such as arthritis, whilst MT-MMPs, other members of the MMP family have been shown to be key enzymes in the activation of gelatinase A (H Sato et al (1994), Nature, 370:61-65). Gelatinase A is an important enzyme in the growth and metastasis of tumours (such as defined above).

The degradation of β-Amyloid Precursor Protein (APP) has been shown to generate amyloid plaques, a major constituent of the senile plaques, found in patients with Alzheimers Disease (AD). Two recent publications have identified metalloproteinase enzymes that cleave APP to the amyloid plaque (C R Abraham et al (1994), Biochemistry, 33:192-19; G Huber et al (1994), Biochem. Biophys. Res. Comm., 201 (1):45-53).

As appreciated by those of skill in the art, the significant proportion of homology between these new enzymes and other MMPs leads to the possibility that a compound that inhibits one enzyme may to some degree inhibit these new enzymes. Therefore, inhibitors encompassed in this invention may be useful in the diseases in which these new enzymes are implicated.

SUMMARY OF THE INVENTION

The invention encompasses novel mercaptoalkylpeptidyl compounds of formula (I) which are useful inhibitors of matrix metalloproteinase and/or TNF mediated diseases including degenerative diseases (such as defined above) and certain cancers.

In a first aspect of the invention there is provided a compound of general formula (I): ##STR1## Wherein:

R¹ is a C₁₋₆ alkyl, C₂₋₆ alkenyl, (C₁₋₆ alkyl) aryl, aryl, (C₁₋₆ alkyl) heteroaryl, heteroaryl or C₁₋₆ alkyl AR⁹ group where A is O, NR⁹ or S(O)_(m) where m=0-2, and R⁹ is H, C₁₋₄ alkyl, aryl, heteroaryl, C₁₋₄ alkyl-aryl or C₁₋₄ alkyl-heteroaryl. If A=NR⁹ the R⁹ groups may be the same or different.

R² is hydrogen or a C₁₋₆ alkyl group;

R³ is a [Alk]_(n) R⁶ group where Alk is a C₁₋₆ alkyl or C₂₋₆ alkenyl group and n is zero or an integer 1;

X is a group NR⁴ R⁵ where R⁴ is hydrogen, aryl, heteroaryl, C₁₋₆ alkyl-heteroaryl, cyclo(C₃₋₆)alkyl, C₁₋₆ alkyl-cyclo(C₃₋₆)alkyl, heterocyclo(C₃₋₆)alkyl or C₁₋₆ alkyl-heterocyclo(C₃₋₆)alkyl, or the group C₁₋₆ alkyl optionally substituted by amino (NH₂), aryl, arylamino, protected amino, di (C₁₋₆ alkyl) amino, mono (C₁₋₆ alkyl) amino, CO₂ H, protected carboxyl, carbamoyl, mono (C₁₋₆ alkyl) carbamoyl, di (C₁₋₆ alkyl) carbamoyl, and R⁵ is hydrogen or a C₁₋₆ alkyl group; NR⁴ R⁵ may also form a ring such as in a pyrrolidino, piperidino or morpholino group.

R⁷ is hydrogen or the group R¹⁰ CO where R¹⁰ is a group C₁₋₄ alkyl, C₁₋₄ alkyl-aryl, C₁₋₄ alkyl-heteroaryl, cyclo (C₃₋₆) alkyl, C₁₋₄ alkyl-cyclo (C₃₋₆) alkyl, C₂₋₆ alkenyl, C₂₋₆ alkenyl-aryl, aryl or heteroaryl;

R¹⁴ is OH, NH₂, OR⁸, NHR⁸ or R⁸ ;

R⁸ is aryl (optionally substituted with R¹¹), heteroaryl (optionally substituted with R¹¹), C₁₋₄ alkyl (optionally substituted with R¹¹), C₁₋₄ alkyl-aryl (optionally substituted with R¹¹), C₁₋₄ alkyl-heteroaryl (optionally substituted with R¹¹), cyclo (C₃₋₆) alkyl (optionally substituted with R¹¹), cyclo (C₃₋₆ ) alkenyl (optionally substituted with R¹¹), C₁₋₄ alkyl-cyclo (C₃₋₆) alkyl (optionally substituted with R¹¹), the groups: ##STR2## where p=1-2, or the group; ##STR3## where B and C may be selected from the groups O,S,C(R⁹)₂, or NR⁹ and these may be the same or different;

R⁶ is an optionally substituted cyclo (C₃₋₆) alkyl, cyclo (C₃₋₆) alkenyl, C₁₋₆ alkyl, aryl, C₁₋₆ alkoxy aryl, benzyloxyaryl, heteroaryl, COR⁹, C₁₋₃ alkyl-aryl, C₁₋₃ alkyl-heteroaryl, alkyl-CO₂ R⁹, C₁₋₆ alkyl-NHR⁹, AR⁹, CO₂ R⁹, CONHR¹⁰, NHCOR¹⁰, NHCO₂ R¹⁰ or NHSO₂ R¹⁰, an amidine or guanidine group;

R¹¹ is a SR⁷, COR¹³, SO₂ R⁹ (when R⁹ is not H), SO₂ N(R⁹)₂, N(R⁹)₂, NR⁹ R¹², OR⁹, COR⁹, phthalimido or succinimido group.

R¹² is hydrogen or a COR⁹, CO₂ R⁹, CONHR⁹ or SO₂ R⁹ (where R⁹ is not H) group;

R¹³ is a OH, OC₁₋₄ alkyl, O(C₁₋₄ alkyl) aryl, N(R⁹)₂ (in which R⁹ is the same or different);

and the salts, solvates and hydrates thereof.

Preferred compounds of the invention include those in which, independently or in any combination have:

R¹ is C₁₋₆ alkyl or C₁₋₄ alkyl-AR⁹ where A is S(O)_(m), NR⁹, or O and m=0,1 or 2, and R⁹ is H, C₁₋₄ alkyl, aryl or heteroaryl;

R² is H or C₁₋₄ alkyl;

R³ is [Alk]_(n) R⁶ where n=0 or 1, Alk is C₁₋₄ alkyl and R⁶ is C₁₋₄ alkyl, C₁₋₃ alkyl-aryl, C₁₋₃ alkyl-heteroaryl, CO₂ R⁹, AR⁹, CONHR¹⁰, NHCOR¹⁰, NHCO₂ R¹⁰ or NHSO₂ R¹⁰, an amidine or guanidine group;

R⁵ is H;

R⁴ is H, C₁₋₆ alkyl, aryl, heteroaryl, C₁₋₆ alkyl-aryl, C₁₋₆ alkyl-heteroaryl or C₁₋₄ alkyl-N(R⁹)₂ ;

NR⁴ R⁵ may form a 5-7 membered ring such as a pyrrolidine, piperidine or morpholine;

R⁷ is H or R¹⁰ CO where R¹⁰ is C₁₋₄ alkyl or aryl;

R⁸ is C₁₋₄ alkyl-R¹¹, C₁₋₄ alkenyl-R¹¹, cyclo(C₃₋₆)alkyl-R¹¹ or C₁₋₄ alkyl;

R¹¹ is COR¹³, NR⁹ R¹², N(R⁹)₂, phthalimido or succinimido;

R¹² is COR⁹, CO₂ R⁹ (provided R⁹ is not H), or SO₂ R⁹ (provided R⁹ is not H);

R¹³ is OH, OC₁₋₄ alkyl or N(R⁹)₂ ;

and R¹⁴ is OH or R⁸ ;

Compounds of the invention have IC₅₀ values below 50 μM against the MMP enzymes and/or below 50 μM in the whole cell assay of TNF inhibition.

It will be appreciated that the compounds according to the invention can contain one or more asymmetrically substituted carbon atoms, for example those marked with an asterisk in formula (I). The presence of one or more of these asymmetric centres in a compound of formula (I) can give rise to stereoisomers, and in each case the invention is to be understood to extend to all such stereoisomers, including enantiomers and diastereomers, and mixtures including racemic mixtures thereof.

In the formulae herein, the ˜ line is used at a potential asymmetric centre to represent the possibility of R- and S- configurations, the < line and the . . . line to represent a unique configuration at an asymmetric centre.

As used in this specification, alone or in combination, the term "C₁₋₆ alkyl" refers to a straight or branched chain alkyl moiety having from one to six carbon atoms, including for example, methyl, ethyl, propyl, isopropyl, butyl, tert-butyl, pentyl, hexyl and the like.

The term "C₁₋₄ alkyl" refers to a straight or branched chain alkyl moiety having from one to four carbon atoms, including for example, methyl, ethyl, propyl, isopropyl, butyl, tert-butyl and the like.

The term "C₂₋₆ alkenyl" refers to a straight or branched chain alkyl moiety having two to six carbon atoms and having in addition one double bond, of either E or Z stereochemistry where applicable. This term would include for example, vinyl, 1-propenyl, 1- and 2- butenyl, 2- methyl-2-propenyl etc.

The term "cyclo (C₃₋₆) alkyl" refers to a saturated alicyclic moiety having from three to six carbon atoms and includes for example cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl and the like.

The term "cyclo (C₃₋₆) alkenyl" refers to an alicyclic moiety having from three to six carbon atoms and having in addition one double bond. This term would include for example cyclopentenyl or cyclohexenyl.

The term "heterocyclo (C₄₋₆) alkyl" refers to a saturated heterocyclic moiety having from three to six carbon atoms and one or more heteroatom from the group N, O, S and includes for example azetidinyl, pyrrolidinyl, tetrahydrofuranyl, piperidinyl and the like.

There term "aryl" means an optionally substituted phenyl or naphthyl group with the substituent(s) being selected, for example, from halogen, trifluoromethyl, C₁₋₆ alkyl, alkoxy, phenyl and the like.

The term "halogen" means fluorine, chlorine, bromine or iodine.

The terms "protected amino" and "protected carboxy" mean amino and carboxy groups which are protected in a manner familiar to those skilled in the art. For example, an amino group can be protected by a benzyloxycarbonyl, tert-butoxycarbonyl, acetyl or like groups, or in the form of a phthalimido or like group. A carboxyl group can be protected in the form of a readily cleavable ester such as the methyl, ethyl, benzyl or tert-butyl ester.

The term "alkoxy" refers to a straight chain or branched chain alkoxy group containing a maximum of six carbon atoms, such as methoxy, ethoxy, propoxy, isopropoxy, butoxy, tert-butoxy and the like.

The term "C₀₋₄ alkyl" refers to a straight chain or branched chain alkoxy group containing a maximum of four carbon atoms, such as methyl, ethyl, propyl, propyl, butyl, tert-butyl and the like.

The term "heteroaryl" refers to aromatic ring systems of five to ten atoms or which at least one atom is selected from the group, O, N, or S and includes for example furanyl, thiophenyl, pyridyl, indolyl, quinolyl and the like.

The term "optionally substituted" refers to a group unsubstituted or substituted with a group taken form but not limited to halogen, trifluoromethyl, C₁₋₆ alkyl, phenyl or a group R¹¹, where R¹¹ has been defined previously, and the like.

Salts of compounds of formula (I) include pharmaceutically acceptable salts, for example acid addition salts derived from inorganic or organic acids, such as hydrochlorides, hydrobromides, p-toluenesulphonates, phosphates, sulphates, perchlorates, acetates, trifluoroacetates, propionates, citrates, malonates, succinates, lactates, oxalates, tartrates and benzoates.

Salts may also be formed with bases. Such salts include salts derived from inorganic or organic bases, for example alkali metal salts such as magnesium or calcium salts, and organic amine salts such as morpholine, piperidine, dimethylamine or diethylamine salts.

When the "protected carboxy" group in compounds of the invention is an esterified carboxyl group, it may be a metabolically labile ester of formula CO₂ R¹⁵ where R¹⁵ may be an ethyl, benzyl, phenethyl, phenylpropyl, α or β-naphthyl, 2,4-dimethylphenyl, 4-tert-butylphenyl, 2,2,2-trifluoroethyl, 1-(benzyloxy)benzyl, 1-(benzyloxy)ethyl, 2-methyl-1-propionyloxypropyl, 2,4,6-trimethylbenzyloxymethyl or pivaloyloxymethyl group.

Compounds of the general formula (I) may be prepared by any suitable method known in the art and/or by the following processes, which itself forms part of the invention.

According to a second aspect of the invention, there is provided a process for preparing a compound of general formula (I) as defined above. It will be appreciated that where a particular stereoisomer of formula (I) is required, the synthetic processes described herein may be used with the appropriate homochiral starting material and/or isomers maybe resolved from mixtures using conventional separation techniques (eg. HPLC).

The compounds according to the invention may be prepared by the following process. In the description and formulae below the groups R¹, R², R³, R⁴, R⁵, R⁶, R⁷, R⁸, R⁹, R¹⁰, R¹¹, R¹², R¹³, R¹⁴, R¹⁵, A, B, C and X are as defined above, except where otherwise indicated. It will be appreciated that functional groups, such as amino, hydroxyl or carboxyl groups, present in the various compounds described below, and which it is desired to retain, may need to be in protected form before any reaction is initiated. In such instances, removal of the protecting group may be the final step in a particular reaction. Suitable protecting groups for such functionality will be apparent to those skilled in the art. For specific details see "Protective Groups in Organic Synthesis", Wiley Interscience, T W Greene, P G M Wuts.

Thus the process required for preparing compounds of general formula (I) comprises of:

deprotecting (for example by hydrolysis) a compound of general formula (II): ##STR4##

Wherein R⁷ represents a suitable protecting group (eg tert-butyl, trityl, acetate or benzoate).

It will be appreciated that where a particular stereoisomer or formula (I) is required, this may be obtained by conventional resolution techniques such as high performance liquid chromatography. Where desired, however, appropriate homochiral starting materials may be used in the coupling reaction to yield a particular stereoisomer of formula (I). This is exemplified below.

Intermediates of general formula (II) may be prepared by coupling an acid of formula (III): ##STR5##

Wherein R⁷ is as defined above, or an active derivative thereof, with an amine of formula (IV): ##STR6##

Active derivatives of acids of formula (III) include for example acid anhydrides or acid halides, such as acid chlorides.

The coupling reaction may be performed using standard conditions for amination reactions of this type. Thus, the reaction may be achieved in a solvent, for example an inert organic solvent such as an ether, eg. a cyclic ether such as tetrahydrofuran, an amide eg. a substituted amide such as dimethylformamide, or a halogenated hydrocarbon such as dichloromethane at a low temperature eg. -30° C. to ambient temperature, such as -20° C. to 0° C., optionally in the presence of a base, eg. an organic base such as an amine, eg. triethylamine or a cyclic amine such as N-methylmorpholine. Where an acid of formula (III) is used, the reaction may additionally be performed in the presence of a condensing agent, for example a diimide such as N,N'-dicyclohexylcarbodiimide, advantageously in the presence of a triazole such as 1-hydroxybenzotriazole. Alternatively, the acid may be reacted with a chloroformate for example ethylchloroformate, prior to reaction with the amine of formula (IV).

The amine of general formula (IV) may be prepared by reductive alkylation of the amine of formula (V): ##STR7## with an aldehyde of formula (VI): ##STR8## wherein R¹⁶ consists of C₂₋₄ alkyl (optionally substituted with R¹¹), C₂₋₄ alkyl-aryl (optionally substituted with R¹¹), C₂₋₄ alkyl-heteroaryl (optionally substituted with R¹¹), C₂₋₄ alkyl-cyclo (C₃₋₆) alkyl (optionally substituted with R¹¹), the groups: ##STR9## where p=1-2, the group: ##STR10## where B and C may be selected from the groups O,S,C(R⁹)₂, or NR⁹ and these may be the same or different;

R¹¹ is SR⁷, COR¹³, SO₂ R¹³, N(R⁹)₂, NR⁹ R¹², OR⁹, COR⁹, phthalimido or succinimido;

Where R⁷, R⁹, R¹², R¹³ are described previously.

Amines of general formula (IV) may also be prepared by alkylation of the amine (V) with compounds of general formula (VII):

    R.sup.14 --Y                                               (VII)

wherein Y represent a suitable leaving group (eg. a halogen such as bromide, or an alkylsulphonate ester such as methanesulphonate).

The amine of general formula (V) may be prepared by coupling an acid of formula (VIII), or an active derivative thereof: ##STR11## with an amine of formula (IX): ##STR12##

Followed by removal of any protecting groups.

Active derivatives of acids of formula (VIII) include for example acid anhydrides or acid halides such as acid chlorides as outlined earlier.

Amino acids and their derivatives as depicted by general formulae (VIII) and (IX) can be obtained in the optically pure or racemic form. In the homochiral form they provide asymmetric building blocks for the enantiospecific synthesis of compounds of general formula (I). Many of these derivatives can be readily obtained from commercially available starting materials using methods known to those skilled in the art. (See "The Practice of Peptide Synthesis" by M. Bodanszk et al, Springer Verlag, New York, 1984 and P. L. Durette, WO92/213460).

Particularly useful when R¹⁴ is aryl or heteroaryl, in a further extension to the present invention, amines of general formula (IV) may be prepared by nucleophilic substitution of compounds of formula (X): ##STR13## where in Z represents a suitable leaving group (eg. a halide such as bromide or an alkylsulphonate ester such as trifluoromethanesulphonate) and R¹⁵ represents an alkyl group (such as methyl, ethyl, tert-butyl, benzyl etc)

with an amine of general formula (XI):

    R.sup.14 --NH.sub.2                                        (XI)

Followed by de-esterification and coupling to an amine of formula (IX) as described previously.

Also, as a further extension to the current invention, compounds of general formula (II) may be prepared by nucleophilic substitution of compounds of formula (XII): ##STR14## wherein Z represent a suitable leaving group as described previously, with a thiol of general formula (XIII):

    R.sup.7 --SH                                               (XIII)

Wherein R⁷ represent a suitable protecting group (eg. tert-butyl, trityl, benzoate or acetate), using standard conditions known to those skilled in the art as exemplified by C. Campion et al, WO 90/9005719.

Thiols of general formula (XIII) may be obtained from commercially available starting materials using methods known to those skilled in the art. Many thiols of general formula (XIII) are also commercially available.

Compounds of general formula (XII) may be prepared by coupling an acid of general formula (XIV): ##STR15## wherein Z is defined above (or suitable protected versions thereof) or an active derivative thereof, with an amine of formula (IV) using similar coupling conditions to those described for the preparation of compounds of formula (II).

Compounds of formula (I) may also be prepared by interconversion of other compounds of formula (I). Thus, for example, a compound of formula (I) wherein R¹ is a C₁₋₆ alkyl group may be prepared by hydrogenation (using palladium on carbon in suitable solvent, such as an alcohol--eg ethanol) of a compound of formula (I) wherein R¹ is a C₂₋₆ alkenyl group. A further example would include a compound of formula (I) wherein R⁷ is a group R¹⁰ CO may be prepared by acylation (using a suitable acid chloride R¹⁰ COCl, in the presence of a base such as a triethylamine in a suitable solvent, such as a chlorinated solvent--eg dichloromethane) of a compound of formula (I) wherein R⁷ is H.

Any mixtures of final products or intermediates obtained can be separated on the basis of the physico-chemical differences of the constituents, in a known manner, into the pure final products or intermediates, for example by chromatography, distillation, fractional crystallization, or by formation of a salt if appropriate or possible under the circumstances.

Compounds according to the invention exhibit in vitro inhibition of TNF release by cells. The compounds according to the invention may also exhibit in vitro inhibiting activities with respect to matrix metalloproteinases such as stromelysin, collagenase and gelatinase. The activity and selectivity of the compounds may be determined by use of the appropriate enzyme inhibition test, for example as described in Example A hereinafter.

This invention also relates to a method of treatment for patients (including man and/or mammalian animals raised in the dairy, meat or fur industries or as pets) suffering from disorders or diseases which can be attributed to stromelysin as previously described, and more specifically, a method of treatment involving the administration of the matrix metalloproteinase inhibitors of formula (I) as the active constituents.

Accordingly, the compounds of formula (I) can be used among other things in the treatment of osteoarthritis and rheumatoid arthritis, and in diseases and indications resulting from the over-expression of these matrix metalloproteinases such as found in certain metastatic tumour cell lines.

As mentioned above, compounds of formula (I) are useful in human or veterinary medicine since they are active as inhibitors of TNF and/or MMPs. Accordingly in another aspect, this invention concerns:

a method of management (by which is meant treatment of prophylaxis) of disease or conditions mediated by TNF and/or MMPs in mammals, in particular in humans, which method comprises administering to the mammal an effective, amount of a compound of formula (I) above, or a pharmaceutically acceptable salt thereof; and

a compound of formula (I) for use in human or veterinary medicine, particularly in the management (by which is meant treatment or prophylaxis) of diseases or conditions mediated by TNF and/or MMPs; and

the use of a compound of formula (I) in the preparation of an agent for the management (by which is meant treatment or prophylaxis) of diseases or conditions mediated by TNF and/or MMPs.

The disease or conditions referred to above include inflammatory diseases, autoimmune diseases cancer, cardiovascular diseases, diseases involving tissue breakdown such as rheumatoid arthritis, osteoarthritis, osteoporosis, neurodegeneration, Alzheimer's disease, atherosclerosis, congestive heart failure, stroke, vasculitis, Crohn's disease, ulcerative colitis, multiple sclerosis, periodontitis, gingivitis and those involving tissue breakdown such as bone resportion, haemorrhage, coagulation, acute phase response, cachexia and anorexia, acute infections, HIV infections, fever, shock states, graft versus host reactions, dermatological conditions, surgical wound healing, psoriasis, atopic dermatitis, epidermolysis bullosa, tumour growth, angiogenesis and invasion by secondary metastases, ophthalmological disease, retinopathy, corneal ulceration, reperfusion injury, migraine, meningitis, asthma, rhinitis, allergic conjunctivitis, eczema and anaphylaxis.

For the treatment of rheumatoid arthritis, osteoarthritis, and in diseases and indications resulting from the over-expression of matrix metalloendoproteinases such as found in certain metastatic tumour cell lines or other diseases mediated by the matrix metalloendoproteinases or increased TNF production, the compound of formula (I) may be administered orally, topically, parenterally, by inhalation spray or rectally in dosage unit formulations containing non-toxic pharmaceutically acceptable carriers, adjuvants and vehicles. The term parenteral as used herein includes subcutaneous injections, intravenous, intramuscular, intrasternal injection or infusion techniques. In addition to the treatment of warm-blooded animals such as mice, rates, horses, cattle, sheep, dogs, cats etc, the compounds of the invention are effective in the treatment of humans.

The pharmaceutical composition containing the active ingredient may be in a form suitable for oral use, for example, as tablets, troches, lozenges, aqueous or oily suspensions, dispersible powders or granules, emulsions, hard or soft capsules, or syrups or elixirs. Compositions intended for oral use may be prepared according to any method known to the art for the manufacture of pharmaceutical compositions and such compositions may contain one or more agents selected from the group consisting of sweetening agents, flavouring agents, colouring agents and preserving agents in order to provide pharmaceutically elegant and palatable preparations. Tablets contain the active ingredient in admixture with non-toxic pharmaceutically acceptable excipients which are suitable for the manufacture of tablets. These excipients may be for example, inert diluents, such as calcium carbonate, sodium carbonate, lactose, calcium phosphate or sodium phosphate; granulating and disintegrating agents, for example corn starch, or alginic acid; binding agents, for example starch, gelatin or acacia, and lubricating agents, for example magnesium stearate, stearic acid or talc. The tablets may be uncoated or they may be coated by known techniques to delay disintegration and absorption in the gastrointestinal tract and thereby provide a sustained action over a longer period. For example, a time delay material such as glyceryl monostearate or glyceryl distearate may be employed. They may also be coated by the techniques described in the U.S. Pat. Nos. 4,256,108; 4,166,452; and 4,265,874 to form osmotic therapeutic tablets for control release.

Formulations for oral use may also be presented as hard gelatin capsules wherein the active ingredient is mixed with an inert solid diluent, for example calcium carbonate, calcium phosphate or kaolin, or as soft gelatin capsules wherein the active ingredient is mixed with water or an oil medium, for example peanut oil, liquid paraffin or olive oil.

Aqueous suspensions contain the active materials in admixture with excipients suitable for the manufacture of aqueous suspensions. Such excipients are suspending agents, for example sodium carboxymethylcellulose, methylcellulose, hydroxy- propylmethylcellulose, sodium alginate polyvinyl-pyrrolidone, gum tragacanth and gum acacia; dispersing or wetting agents may be a naturally occurring phosphatide, for example lecithin, or condensation products of an alkylene oxide with fatty acids, for example polyoxyethylene stearate, or condensation products of ethylene oxide with long chain aliphatic alcohols, for example heptadecaethyleneoxycetanol, or condensation products of ethylene oxide with partial esters derived from fatty acids and a hexitol such a polyoxyethylene with partial esters derived from fatty acids and hexitol anhydrides, for example polyoxyethylene sorbitan monooleate. The aqueous suspensions may also contain one or more preservatives, for example ethyl, or n-propyl, p-hydroxybenzoate, one or more colouring agents, one or more flavouring agents, and one or more sweetening agents, such as sucrose or saccharin.

Oily suspensions may be formulated by suspending the active ingredient in a vegetable oil, for example arachis oil, olive oil, sesame oil or coconut oil, or in a mineral oil such as liquid paraffin. The oily suspensions may contain a thickening agent, for example beeswax, hard paraffin or cetyl alcohol. Sweetening agents such as those set forth above, and flavouring agents may be added to provide a palatable oral preparation. These compositions may be preserved by the addition of an anti-oxidant such as ascorbic acid.

Dispersible powders and granules suitable for preparation of an aqueous suspension by the addition of water provide the active ingredient in admixture with a dispersing or wetting agent, suspending agent and one or more preservatives. Suitable dispersing or wetting agents and suspending agents are exemplified, for example sweetening, flavouring and colouring agents, may also be present.

The pharmaceutical compositions of the invention may also be in the form of oil-in-water emulsions. The oily phase may be a vegetable oil, for example olive oil or arachis oil, or a mineral oil, for example liquid paraffin or mixtures of these. Suitable emulsifying agents may be naturally-occurring gums, for example gum acacia or gum tragacanth, naturally-occurring phosphatides, for example soya bean, lecithin, and esters or partial esters derived from fatty acids and hexitol anhydrides, for example sorbitan monooleate and condensation products of the said partial esters with ethylene oxide, for example polyoxyethylene sorbitan monooleate. The emulsions may also contain sweetening and flavouring agents.

Syrups and elixirs may be formulated with sweetening agents, for example gycerol, propylene glycol, sorbitol or sucrose. Such formulations may also contain a demulcent, a preservative and flavouring and colouring agents. The pharmaceutical compositions may be in the form of a sterile injectable aqueous or oleagenous suspension. This suspension may be formulated according to the known art using those suitable dispersing or wetting agents and suspending agents which have been mentioned above. The sterile injectable preparation may also be in a sterile injectable solution or suspension in a non-toxic parenterally-acceptable diluent or solvent, for example as a solution in 1,3-butane diol. Among the acceptable vehicles and solvents that may be employed are water, Ringer's solution and isotonic sodium chloride solution. In addition, sterile, fixed oils are conventionally employed as a solvent or suspending medium. For this purpose any bland fixed oil may be employed including synthetic mono- or diglycerides. In addition, fatty acids such as oleic acid find use in the preparation of injectables.

The compounds of formula (I) may also be administered in the form of suppositories for rectal administration of the drug. These compositions can be prepared by mixing the drug with a suitable non-irritating excipient which is solid at ordinary temperatures but liquid at the rectal temperature and will therefore melt in the rectum to release the drug. Such materials are cocoa butter and polyethylene glycols.

For topical use, creams, ointments, jellies, solutions or suspensions, etc containing the compounds of Formula (I) are employed. (For purposes of this application, topical application shall include mouth washes and gargles).

Dosage levels of the order of from about 0.05 mg to about 140 mg per kilogram of body weight per day are useful in the treatment of the above-indicated conditions (about 2.5 mg to about 7 gms per patient per day). For example, inflammation may be effectively treated by the administration of from about 0.01 to 50 mg of the compound per kilogram of body weight per day (about 0.5 mg to about 3.5 gms per patient per day).

The amount of active ingredient that may be combined with the carrier materials to produce a single dosage form will vary depending upon the host treated and the particular mode of administration. For example, a formulation intended for the oral administration of humans may vary from about 5 to about 95 percent of the total composition. Dosage unit forms will generally contain between from about 1 mg to about 500 mg of an active ingredient.

It will be understood, however, that the specific dose level for any particular patient will depend upon a variety of factors including the activity of the specific compound employed, the age, body weight, general health, sex, diet time of administration, route of administration, rate of excretion, drug combination and the severity of the particular disease undergoing therapy.

The following non-limiting Examples are intended to illustrate the preparation of compounds of Formula (I), and as such are not intended to limit the invention as set forth in the claims.

In the Examples, the following abbreviations are used:

    ______________________________________                                         RT    Room temperature                                                           EDC 1-(3-Dimethylaminopropyl)-3-ethyl carbodiimide hydrochloride                    TNFα  Tumour necrosis factor α                                ELISA Enzyme linked immunosorbent assay                                        LPS Lipopolysaccharide (Endotoxin)                                           ______________________________________                                    

Intermediate 1 3-Phthalimidopropanaldehyde diethyl acetal

A solution of potassium phthalmide (2 g, 10.8 mmol) and 3-bromopropanaldehyde diethyl acetal (1.8 g, 10.8 mmol) in dry dimethylformamide (20 ml) was heated at 110° C. for 2 h. The mixture was allowed to cool then partitioned between ethyl acetate (70 ml) and water (20 ml). The organic extract was washed with water (3×20 ml), dried (MgSO₄) and evaporated in vacuo to provide the title compound as a white solid (2.99 g, 84%).

Tlc: EtOAc/hexanes (1:4), R_(f) 0:43

Intermediate 2 3-Phthalimidopropanaldehyde

A solution of intermediate 1 (2.5 g, 9.2 mmol) in ethanol (15 ml) and 1M hydrochloric acid (15 ml) was heated under reflux, then ethanol distilled off until the distillation head temperature reached 99° C. The separated oil was then extracted into dichloromethane (2×25 ml), the combined extracts dried (MgSO₄) and evaporated in vacuo to provide the title compound as a white solid (1.7 g, 92%).

Tlc: EtOAc/hexanes (1:4), R_(f) 0.03

Similarly prepared was:

Intermediate 3 2-Phthalimidoacetaldehyde

From commercially available 2-phthalimidoacetaldehyde diethylacetal, as a white solid (2.1 g; 99%).

Tlc: EtOAc/hexane (1:4), R_(f) 0.10

Intermediate 4 3-Phthalimidopropyl-L-leucyl-L-phenylalanine N-methyl amide

Sodium triacetoxyborohydride (911 mg, 4.3 mmol) was added in a single portion to a stirred solution of L-leucyl-L-phenylalanine-N-methyl amide (500 mg, 1.72 mmol) and intermediate 2 (348 mg, 1.72 mmol) in dry 1,2-dichloroethane (20 ml). The mixture was stirred at room temperature for 1 hour before a further portion of sodium triacetoxyborohydride (500 mg, 2.4 mmol) was added. After a further 1 hour the mixture was diluted with dichloromethane (50 ml), washed with saturated sodium bicarbonate (2×30 ml), dried (MgSO₄) and evaporated in vacuo to provide a yellow foam. Purification by column chromatography eluting with 5% methanol in dichloromethane provided the product as a white solid (711 mg, 87%).

Tlc: 5% MeOH/CH₂ Cl₂, R_(f) 0.18

Similarly prepared were:

Intermediate 5 N-(2-Phthalimidoethyl)-L-leucyl-L-phenylalanine N-methylamide

From intermediate 3, as a white solid (159 mg; 98%)

Tlc: 5% MeOH-0.1% Et₃ N-CH₂ Cl₂, R_(f) 0.35

Intermediate 6 N-(Methoxycarbonyl)methyl-L-leucyl-L-phenylalanine N-methylamide

From commercially available methyl glyoxalate mono-methylacetal, as a near white solid (780 mg; 58%).

Tlc: EtOAc/CH₂ Cl₂ (1:1), R_(f) 0.17

Intermediate 7 N-[2-(1,1-Dimethylethylmercapto)ethyl]-L-leucyl-L-phenylalanine N-methylamide

From 2-(1,1-dimethylethyl)mercaptoacetaldehyde, as a pale yellow foam (310 mg, 41%).

Tlc: EtOAc/CH₂ Cl₂ (1:1), R_(f) 0.17

Intermediate 8 N-(3-Phthalimidopropyl)-L-valinyl-L-phenylalanine N-methylamide

From intermediate 2 (0.73 g, 3.61 mmol) and L-valinyl-L-phenylalanine N-methylamide, as a white solid (489 mg, 29%).

Tlc: (5% MeOH/CH₂ Cl₂), R_(f) 0.23

Intermediate 9 N-[(1,1-Dimethylethyl)sulphanylacetyl]-N-(methoxycarbonyl)methyl-L-leucyl-L-phenylalanine N-methylamide

From intermediate 6 and 2-(1,1-dimethylethyl)mercaptoacetic acid according to the procedure outlined for example 1, as a colourless foam. (370 mg, 61%).

Tlc: EtOAc/CH₂ Cl₂ (1:1), R_(f) 0.42.

Intermediate 10 N-(Methoxycarbonyl)methyl-N-(2-nitrophenylsulphanylsulphanyl)acetyl-L-leucyl-L-phenylalanine N-methylamide

A solution of intermediate 9 (360 mg, 0.73 mmol) in glacial acetic acid (5 ml) was treated with 2-nitrosulphenyl chloride (140 mg, 0.74 mmol). The mixture was then stirred at room temperature for 3 h. The solvent was evaporated in vacuo and the semi-solid residue purified by column chromatography eluting with 40% ethyl acetate in dichloromethane providing the title compound (310 mg, 72%) as a yellow solid.

Tlc: EtOAc/CH₂ Cl₂ (1:1), R_(f) 0.17

Intermediate 11 N-(Methoxycarbonyl)ethyl-L-leucyl-L-phenylalanine N-methylamide

A solution of L-leucyl-L-phenylalanine N-methylamide (1.09 g) in ethanol (20 ml) was treated with methyl acrylate (0.33 ml). The resulting colourless solution was heated to 70° C. over 7.5 h. The crude product was purified by flash silica chromatography, eluting with ethyl acetate/methanol (9:1) to provide the title compound was isolated as a white solid (0.482 g).

Tlc: EtOAc/MeOH (9:1), R_(f) 0.74

Intermediate 12 N-(Methoxycarbonyl)propyl-L-leucyl-L-phenylalanine N-methylamide

A solution of L-leucyl-L-phenylalanine N-methylamide (1.19 g) in ethanol (24 ml) was treated with methyl 4-iodobutyrate (0.93 g); the resulting colourless solution was heated to 45° C. over 16 h. The crude product was purified by flash silica chromatography, eluting with ethyl acetate/heptane (1:1 to 5:1), to furnish the title compound as an off-white solid (0.42 g).

Tlc: EtOAc/MeOH (9:1), R_(f) 0.41

Intermediate 13 N-Phthalimidomethyl-L-leucyl-L-phenylalanine N-methylamide

A solution of L-leucyl-L-phenylalanine N-methylamide (1.3 g) in dichloromethane (13 ml) was treated with N-bromomethylphthalimide (1.17 g) and sodium iodide (0.06 g). The resulting yellow solution was stirred at room temperature for 16 h. The solution was treated with saturated sodium bicarbonate solution (ca. 8 ml) and extracted with dichloromethane. The crude, organic extracts were preadsorbed onto silica gel and purified by flash silica chromatography, eluting with ethyl acetate/heptane (5:1), to furnish the title compound as a white solid (0.74 g).

Tlc: EtOAc, R_(f) 0.46

Intermediate 14 N-Hydroxy-L-leucine 1,1-dimethylethyl ester

Prepared according to the procedure of Grundke et al, Synthesis 1987, 1115.

Intermediate 15 N-Chloroacetyl-N-hydroxy-L-leucine 1,1-dimethylethyl ester

Chloroacetyl chloride (0.32 ml) was added to a solution of intermediate 14 (0.80 g, 4.2 mmol) in tetrahydrofuran (10 ml) containing solid sodium bicarbonate (600 mg) at 0° C. The mixture was stirred at 0° C. to room temperature for 3 h, then diluted with dichloromethane (100 ml) and washed with sat. sodium bicarbonate, 1N hydrochloric acid and brine, dried (MgSO₄) and evaporated in vacuo to give a colourless solid residue. Purification by column chromatography eluting with ether/hexanes (1:3) gave the title compound as a colourless crystalline solid (1.10 g, 94%).

TLC R_(f) 0.29 (ether/hexanes 1:3).

Intermediate 16 N-Acetylsulphanylacetyl-N-hydroxy-L-leucine 1,1-dimethylethyl ester

Potassium thioacetate (0.90 g) was added to a solution of intermediate 15 (1.10 g, 3.9 mmol) in methanol at RT. The mixture was stirred for 2 h, then evaporated in vacuo. The residue was dissolved in dichloromethane, washed with water and brine, dried (MgSO₄) and evaporated in vacuo to give an orange oil. Purification by column chromatography eluting with hexane/ether (2:1) provided the title compound as colourless solid (0.80 g, 64%).

TLC R_(f) 0.22 (2:1 hexane/ether).

Intermediate 17 N-Acetylsulphanylacetyl-N-hydroxy-L-leucine

Trifluoroacetic acid (10 ml) was added to a solution of intermediate 16 (0.80 g, 2.5 mmol) in dichloromethane (10 ml) at RT and the mixture stirred for 2 h. The solvent was then evaporated and residual trifluoroacetic acid removed by azeotropic distillation with hexanes to provide the title compound as colourless viscous oil (0.60 g).

TLC R_(f) 0.05 (1:1 ether/hexane)

Example 1 N-Acetylsulphanylacetyl-N-(3-phthalimidopropyl)-L-leucyl-L-phenylalanine N-methylamide

Acetylsulphanylacetic acid (310 mg, 2.31 mmol) was dissolved in thionyl chloride (0.3 ml, 4.1 mmol) and the mixture stirred for 15 minutes. Excess thionyl chloride was then evaporated in vacuo to provide an orange oil. A solution of the intermediate acid chloride in dry dichloromethane (1 ml) was added dropwise at 0° C. to a stirred solution of intermediate 4 (372 mg, 0.78 mmol) and triethylamine (0.4 ml, 2.88 mmol) in dry dichloromethane (10 ml). The mixture was then stirred at room temperature overnight. The mixture was diluted with dichloromethane (50 ml) and the solution washed sequentially with 8% sodium bicarbonate (2×30 ml), 2M hydrochloric acid (2×30 ml), water (30 ml) and brine (30 ml), dried (MgSO₄) and evaporated in vacuo to a brown solid. Purification by column chromatography eluting with ethyl acetate/dichloromethane (1:1) provided the product as a white solid (320 mg, 68%).

Tlc: EtOAc/CH₂ Cl₂ (1:1), R_(f) 0.06

Similarly prepared was:

Example 2 N-Acetylsulphanylacetyl-N-(2-phthalimidoethyl)-L-leucyl-L-phenylalanine N-methylamide

From intermediate 5, as a near white solid (98 mg; 52%).

Tlc: EtOAc/CH₂ Cl₂ (6:4) R_(f) 0.27

Example 3 N-Acetylsulphanylacetyl-N-[2-(1,1-dimethylethyl)mercaptoethyl]-L-leucyl-L-phenylalanine N-methylamide

From intermediate 7, as a pale yellow oil (530 mg; 63%).

Tlc: EtOAc/CH₂ Cl₂ (1:1), R_(f) 0.26

Example 4 N-Acetylsulphanylacetyl-N-[b 2-(methoxycarbonyl)ethyl]-L-leucyl-L-phenylalanine N-methylamide

A solution of intermediate 11 (0.448 g) in ethyl acetate (5 ml) at room temperature was treated with acetylsulphanylacetic acid (0.239 g), N-methylmorpholine (0.6 ml), propylphosphonic anhydride (1.314 g of a 50% solution in ethyl acetate) and N,N-dimethylaminopyridine (0.015 g). The resulting yellow solution was stirred at room temperature over 48 h. A deep brown solution resulted which was washed with 2N aqueous hydrochloric acid (ca. 5 ml) and saturated sodium bicarbonate solution (ca. 5 ml), and extracted with ethyl acetate. The crude product was purified by flash silica chromatography, eluting with ethyl acetate/heptane (3:1), to give the title compound as a pale yellow oil (0.486 g).

Tlc: EtOAc, R_(f) 0.74

Example 5 N-Acetylsulphanylacetyl-N-[2-(methoxycarbonyl)propyl]-L-leucyl-L-phenylalanine N-methylamide

A solution of intermediate 12 (0.42 g) in dichloromethane (10 ml) was treated with thioacetic acid (0.22 g) followed by EDAC.HCl (0.23 g). The resulting yellow solution was stirred at room temperature for 16 h. The crude product was preadsorbed onto silica gel and purified by flash silica chromatography, eluting with ethyl acetate/heptane (1:1 to 2.3:1), to furnish the title compound as a white solid (0.35 g).

Tlc: EtOAc, R_(f) 0.51

Example 6 N-Acetylsulphanylacetyl-N-hydroxy-L-leucyl-L-phenylalanine N-methylamide

Intermediate 17 (0.60 g, 2.5 mmol) and phenylalanine N-methylamide (0.60 g, 1.35 eq.) were dissolved in tetrahydrofuran at 0° C. and EDC (0.48 g) and N-hydroxybenzotriazole (0.34 g) were added. The resulting mixture was stirred at RT for 3 h, then evaporated in vacuo. The residue was dissolved in dichloromethane, washed with sat. sodium bicarbonate, 0.5 N hydrochloric acid and brine, dried (MgSO₄) and evaporated in vacuo. The crude product was purified by column chromatography eluting with ethyl acetate to give the title compound, as colourless glass (0.62 g, 56%).

TLC R_(f) 0.42 (EtOAc)

Example 7 N-(3-Phthalimidopropyl)-N-sulphanylacetyl-L-leucyl-L-phenylalanine N-methylamide

A solution of example 1 (150 mg, 0.25 mmol) in anhydrous methanol (3 ml) was treated at 5° C. with sodium methoxide (150 mg, 0.26 mmol) and the mixture stirred for 2 h. The mixture was poured into dichloromethane (20 ml) and the solution washed sequentially with 2M hydrochloric acid (2×10 ml), water (10 ml) and brine (10 ml), dried (MgSO₄) and evaporated in vacuo to an off-white solid (128 mg, 92%).

Tlc: EtOAc/CH₂ Cl₂ (1:1) R_(f) 0.18

Similarly prepared were:

Example 8 N-Sulphanylacetyl-N-(2-phthalimidoethyl)-L-leucyl-L-phenylalanine N-methylamide

From example 2, as a near white solid (47 mg; 77%).

Tlc: MeOH/CH₂ Cl₂ (5:95), R_(f) 0.39

Example 9 N-Sulphanylacetyl-N-hydroxy-L-leucyl-L-phenylalanine N-methylamide

From example 6, as a colourless foam (89%).

TLC R_(f) 0.38 (EtOAc)

Intermediate 18 N-Acetylsulphanylacetyl-N-[2-(2-nitrophenyl)sulphanylsulphanylethyl]-L-leucyl-L-phenylalanine N-methylamide

A solution of intermediate 10 (190 mg, 0.34 mmol) in glacial acetic acid (5 ml) was treated with 2-nitrophenylsulphenyl chloride (80 mg, 0.42 mmol) and the mixture stirred at room temperature for 3 h. The solvent was evaporated in vacuo and the semi-solid residue purified by column chromatography eluting with ethyl acetate/hexane (1:1) providing the title compound (350 mg, 94%) as a bright yellow solid.

Tlc: EtOAc/CH₂ Cl₂ (1:1), R_(f) 0.21

Example 10 N-(2-Acetylsulphanylethyl)-N-sulphanylacetyl-L-leucyl-L-phenylalanine N-methylamide

A solution of intermediate 18 (250 mg, 4.03 mmol) in a mixture of methanol (3 ml) and chloroform (10 ml) was treated at 0° C. with sodium borohydride (76 mg, 1.97 mmol) and the mixture allowed to warm to room temperature over 0.5 h. The mixture was then washed sequentially with water (10 ml), 1M hydrochloric acid (10 ml), water (10 ml) and brine (10 ml) before drying (MgSO₄) and evaporating in vacuo to provide the product as an off-white solid (175 mg; 97%).

Tlc: EtOAc/CH₂ Cl₂ (1:1), R_(f) 0.24

Example A

Collagenase Inhibition Activity

The potency of compounds of general formula (I) to act as inhibitors of collagenase was determined by the procedure of Cawston and Barrett (Anal. Biochem., 99:340-345, 1979) whereby a 1 mM solution of the inhibitor being tested or dilutions thereof was incubated at 37° C. for 16 hours with collagen and collagenase (buffered with 50 mM Tris, pH 7.6 containing 5 mM CaCl₂, 0.05% Brij 35, 60 mM NaCl and 0.02% NaN₃). The collagen was acetylated ³ H or ¹⁴ C-collagen prepared by the method of Cawston and Murphy (Methods in Enzymology, 80:711, 1981). The choice of radiolabel did not alter the ability of collagenase to degrade the collagen substrate. The samples were centrifuged to sediment undigested collagen and an aliquot of the radioactive supernatant removed for assay on a scintillation counter as a measure of hydrolysis. The collagenase activity in the presence of 1 mM inhibitor, or a dilution thereof, was compared to activity in a control devoid of inhibitor and the results reported as that inhibitor concentration effecting 50% inhibition of the collagenase (IC₅₀).

Example B

Stromelysin Inhibition Activity

The potency of compounds of general formula (I) to act as inhibitors of stromelysin was determined using the procedure of Nagase et al (Methods in Enzymology Vol 254, 1994), whereby a 0.1 mM solution of the inhibitor being tested or dilutions thereof was incubated at 37° C. for 16 hours with stromelysin and ³ H transferrin (buffered with 50 mM Tris, pH 7.6 containing 10 mM CaCl₂, 150M NaCl, 0.05% Brij, 35, and 0.02% NaN₃). The transferrin was carboxymethylated with ³ H iodoacetic acid. The stromelysin activity in the presence of 1 mM, or a dilution thereof, was compared to activity in a control devoid of inhibitor and the results reported as that inhibitor concentration effecting 50% inhibition of the stromelysin (IC₅₀).

Example C

Gelatinase Inhibition Activity

The potency of the compounds of general formula (I) to act as inhibitors of gelatinase was determined using the procedure of Harris & Krane (Biochem Biophys. Acta, 258:566-576, 1972), whereby a 1 mM solution of the inhibitor being tested or dilutions thereof was incubated at 37° C. for 16 hours with gelatinase and heat denatured ³ H or ¹⁴ C-acetylated collagen (buffered with 50 mM Tris, pH 7.6 containing 5 mM CaCl₂, 0.05% Brij 35 and 0.02% NaN₃). The ³ H or ¹⁴ C gelatin was prepared by denaturing ³ H or ¹⁴ C-collagen produced according to the method of Cawston and Murphy (Methods in Enzymology, 80:711, 1981) by incubation at 60° C. for 30 minutes. Undigested gelatin was precipitated by addition of trichloroacetic acid and centrifugation. The gelatinase activity in the presence of 1 mM, or dilution thereof, was compared to the activity in a control devoid of inhibitor and results reported as that inhibitor concentration effecting 50% inhibition of the gelatinase (IC₅₀).

Example D

MMP Inhibition Activity-Fluorimetric Assay

The potency of compounds of general formula (I) to act as inhibitors of collagenase-1(MMP-1), collagenase-2 (MMP-8), gelatinase-A (MMP-2), gelatinase-B (MMP-9) and stromelysin-1(MMP-3) was determined using the following procedure: Inhibitors were dissolved in dimethylsulphoxide containing 0.02% b-mercaptoethanol and serial dilutions are prepared. Activated enzyme was incubated in assay buffer containing 50 mM Tris, pH 7.4, 5 mM CaCl₂, 0.002% NaN₃ and Brij 35 in the presence and absence of inhibitor. Samples were preincubated at 37° C. for 15 minutes before the addition of the fluorimetric substrate (Mca-Pro-Leu-Dpa-Ala-Arg-NH₂) to a final concentration of 10 mM. The assay was incubated for 90 minutes at 37° C. and then read in a Fluoroscan II at I_(ex) (355 nm) and I_(em) (460 nm). The enzyme activity was compared to activity in a control devoid of inhibitor and the results reported as that inhibitor concentration effecting 50% inhibition of the stromelysin (IC₅₀).

Example E

Inhibition of TNFα Production

The potency of the compounds of general formula (I) to act as inhibitors of the production of TNFa was determined using the following procedure. A 1 mM solution of the inhibitor being tested or dilutions thereof was incubated at 37° C. in an atmosphere of 5% CO₂ with THP-1 cells (human monocytes) suspended in RPM1 1640 medium and 20 μM β-mercaptoethanol at a cell density of 1×10⁶ /ml and stimulated with 5 μg/ml final concentration of LPS. After 18 hours the supernatant was assayed for the levels of TNFα using a commercially available ELISA kit (R & D Systems). The activity in the presence of 0.1 mM inhibitor or dilutions thereof was compared to activity in a control devoid of inhibitor and results reported as that inhibitor concentration effecting 50% inhibition of the production of TNFa.

Example F

Adjuvant Arthritic Rat Model

Compounds of general formula (I) were evaluated in an adjuvant arthritis model in the rat based on the methods employed by B. B. Newbould (1963), Br. J. Pharmacol, 21, 127-136 and C. M. Pearson and F. D. Wood (1959), Arthritis Rheum, 2, 440-459. Briefly, male Wistar rats (180-200 g) were injected at the base of the tail with Freund's adjuvant. Twelve days later the responding animals were randomised into experimental groups. Compounds of general formula (I) were dosed either orally as a suspension in 1% methyl cellulose or intraperitoneally in 0.2% carboxymethylcellulose from day 12 to the end of the experiment on day 22. Hind paw volumes were measured every two days from day 12 onwards and X-rays were taken of the hind feet on completion of the experiment. Results were expressed as the percent increase of foot volume over day 12 values.

Example G

Mouse Ovarian Carcinoma Xenograft Model

Compounds of general formula (I) were evaluated in an ovarian carcinoma xenograft model of cancer, based on that described by B. Davies et al (1993), Cancer Research, 53, 2087-2091. This model, in brief, consists of inoculating female nu/nu mice with 1×10⁹ OVCAR3-icr cells into the peritoneal cavity. Compounds of general formula (I) are administered by the oral route as a suspension in 1% methyl cellulose or intraperitoneally as a suspension in phosphate buffered saline in 0.01% Tween-20. At the conclusion of the experiment (4-5 weeks) the number of peritoneal cells are counted and any solid tumour deposits weighted. In some experiments tumour development is monitored by measurement of tumour specific antigens.

Example H

Rat Mammary Carcinoma Model

Compounds of general formula (I) were evaluated in a HOSP.1 rat mammary carcinoma model of cancer (S. Eccles et al (1995), Cancer Research, in press). This model consists of the intravenous inoculation of female CBH/cbi rats with 2×10⁴ tumour cells into the jugular vein. Compounds of general formula (I) are administered by the oral route as a suspension in 1% methyl cellulose or intraperitoneally as a suspension in phosphate buffered saline in 0.01% Tween-20. At the conclusion of the experiment (4-5 weeks) the animals were killed, the lungs were removed and individual tumours counted after 20 hours fixation in Methacarn. 

What is claimed is:
 1. A compound of the formula (I): ##STR16## wherein: R¹ is a C₁₋₆ alkyl, C₂₋₆ alkenyl, (C₁₋₆ alkyl) aryl, aryl, (C₁₋₆ alkyl) heteroaryl, heteroaryl or C₁₋₆ alkyl AR⁹ group where A is O, NR⁹ or S(O)_(m) where m=0-2, and R⁹ is H, C₁₋₄ alkyl, aryl, heteroaryl, C₁₋₄ alkyl-aryl or C₁₋₄ alkyl-heteroaryl; if A=NR⁹ the R⁹ groups may be the same or different;R² is hydrogen or C₁₋₆ alkyl; R³ is a (Alk)_(n) R⁶ group where Alk is a C₁₋₆ alkyl or C₂₋₆ alkenyl group and n is zero or 1; X is a group NR⁴ R⁵ where R⁴ is hydrogen, aryl, heteroaryl, C₁₋₆ alkyl-heteroaryl, cyclo(C₃₋₆)alkyl, C₁₋₆ alkyl-cyclo(C₃₋₆)alkyl, heterocyclo(C₃₋₆)alkyl or C₁₋₆ alkyl-heterocyclo(C₃₋₆)alkyl, or the group C₁₋₆ alkyl optionally substituted by amino (NH₂), aryl, arylamino, protected amino, di (C₁₋₆ alkyl) amino, mono (C₁₋₆ alkyl) amino, CO₂ H, protected carboxyl, carbamoyl, mono (C₁₋₆ alkyl) carbamoyl, di (C₁₋₆ alkyl) carbamoyl, and R⁵ is hydrogen or a C₁₋₆ alkyl group; or NR⁴ R⁵ forms a ring; R⁷ is hydrogen or the group R¹⁰ CO where R¹⁰ is a group C₁₋₄ alkyl, C₁₋₄ alkyl-aryl, C₁₋₄ alkyl-heteroaryl, cyclo (C₃₋₆ ) alkyl, C₁₋₄ alkyl-cyclo (C₃₋₆) alkyl, C₂₋₆ alkenyl, C₂₋₆ alkenyl-aryl, aryl or heteroaryl; R¹⁴ is OH, NH₂, OR⁸, NHR⁸ or R⁸ ; R⁸ is aryl (optionally substituted with R¹¹), heteroaryl (optionally substituted with R¹¹), C₁₋₄ alkyl substituted with R¹¹, C₁₋₄ alkyl-aryl (optionally substituted with R¹¹), C₁₋₄ alkyl-heteroaryl (optionally substituted with R¹¹), cyclo (C₃₋₆) alkyl (optionally substituted with R¹¹), cyclo (C₃₋₆) alkenyl (optionally substituted with R¹¹), C₁₋₄ alkyl-cyclo (C₃₋₆) alkyl (optionally substituted with R¹¹), the groups: ##STR17## where p=1-2, or the group: ##STR18## where B and C may be selected from the groups O,S,C(R⁹)₂, or NR⁹ and these may be the same or different; R⁶ is an optionally substituted cyclo(C₃₋₆)alkyl, cyclo(C₃₋₆) alkenyl, C₁₋₆ alkyl, aryl, C₁₋₆ alkoxyaryl, benzyloxyaryl, heteroaryl, COR⁹, C₁₋₃ alkyl-aryl, C₁₋₃ alkyl-heteroaryl, alkyl-CO₂ R⁹, C₁₋₆ alkyl-NHR⁹, AR⁹, CO₂ R⁹, CONHR¹⁰, NHCOR¹⁰, NHCO₂ R¹⁰ or NHSO₂ R¹⁰ group, an amidine or guanidine group; R¹¹ is SR⁷, COR¹³, SO₂ R⁹ (when R⁹ is not H), SO₂ N(R⁹)₂, N(R⁹)₂, NR⁹ R¹², OR⁹, COR⁹, phthalimido or succinimido; R¹² is hydrogen, COR⁹, CO₂ R⁹, CONHR⁹ or SO₂ R⁹ (where R⁹ is not H); and R¹³ is OH, OC₁₋₄ alkyl, O(C₁₋₄ alkyl)-aryl or N(R⁹)₂ (in which R⁹ is the same or different);and the salts, solvates and hydrates thereof.
 2. The compound of claim 1, where R¹ is C₁₋₆ alkyl or C₁₋₄ alkyl-AR⁹ where A is S(O)_(m), NR⁹ or O and m=0,1 or 2, and R⁹ is H, C₁₋₄ alkyl, heteroaryl or aryl.
 3. The compound of claim 1, where R² is H or C₁₋₄ alkyl.
 4. The compound of claim 1, where R³ is (Alk)_(n) R⁶ where n=0 or 1, Alk is C₁₋₄ alkyl and R⁶ is C₁₋₄ alkyl, C₁₋₃ alkyl-aryl, C₁₋₃ alkyl-heteroaryl, AR⁹, CO₂ R⁹, CONHR¹⁰, NHCOR¹⁰, NHCO₂ R¹⁰ or NHSO₂ R¹⁰, an amidine or guanidine group.
 5. The compound of claim 1, where R⁵ is H.
 6. The compound of claim 1, where R⁴ is H, C₁₋₆ alkyl, aryl, heteroaryl, C₁₋₆ alkyl-aryl, C₁₋₆ alkyl-heteroaryl or C₁₋₄ alkyl-N(R⁹)₂.
 7. The compound of claim 1, where NR⁴ R⁵ is a 5-7 membered ring.
 8. The compound of claim 7, wherein NR⁴ R⁵ is pyrrolidine, piperidine or morpholine.
 9. The compound of claim 1, where R⁷ is H or R¹⁰ CO where R¹⁰ is C₁₋₄ alkyl or aryl.
 10. The compound of claim 1, where R⁸ is C₁₋₄ alkyl-R¹¹, C₁₋₄ alkenyl-R¹¹ or cyclo(C₃₋₆)alkyl-R¹¹.
 11. The compound of claim 1, where R¹¹ is COR¹³, NR⁹ R¹², N(R⁹)₂, phthalimido or succinimido.
 12. The compound of claim 1, where R¹² is COR⁹, CO₂ R⁹ (provided R⁹ is not H), or SO₂ R⁹ (provided R⁹ is not H).
 13. The compound of claim 1, where R¹³ is OH, OC₁₋₄ alkyl or N(R⁹)₂.
 14. The compound of claim 1, where R¹⁴ is OH or R⁸.
 15. The compound of claim 1, where R¹⁴ is R⁸ and R⁴ is H or optionally-substituted alkyl.
 16. The compound of claim 1, selected from the group consisting ofN-Acetylsulphanylacetyl-N-(3-phthalimidopropyl)-L-leucyl-L-phenylalanineN-methylamide, N-Acedtylsulphanylacetyl-N-(2-phthalimidoethyl)-L-leucyl-L-phenylalanineN-methylamide, N-Acetylsulphanylacetyl-N-(2-(1,1-dimethylethyl)sulphanylethyl)-L-leucyl-L-phenylalanine N-methylamide, N-Acetylsulphanylacetyl-N-(2-(methoxycarbonyl)ethyl)-L-leucyl-L-phenylalanine N-methylamide, N-sulphanylacetyl-N-(2-phthalimidoethyl)-L-leucyl-L-phenylalanine N-methylamide, and N-(2-Acetylsulphanylethyl)-N-sulphanylacetyl-L-leucyl-L-phenylalanine N-methylamide.
 17. The compound of claim 1, selected from the group consisting ofN-Acetylsulphanylacetyl-N-(2-(methoxycarbonyl)propyl)-L-leucyl-L-phenylalanine N-methylamide and N-(3-Phthalimidopropyl)-N-sulphanylacetyl-L-leucyl-L-phenylalanine N-methylamide.
 18. The compound of claim 1, selected from the group consisting ofN-Acetylsulphanylacetyl-N-hydroxy-L-leucyl-L-phenylalanine N-methylamide and N-Sulphanylacetyl-N-hydroxy-L-leucyl-L-phenylalanine N-methylamide.
 19. The compound of claim 1, in the form of a single enantiomer or diastereomer, or a mixture of such isomers.
 20. The pharmaceutical composition, comprising a compound of claim 1, and a pharmaceutically-acceptable diluent or carrier.
 21. A method for the treatment of a condition that is mediated by TNFα, comprising administering an effective amount of the compound of claim 1 to a person or animal in need of such treatment.
 22. The method according to claim 21, wherein the condition is selected from the group consisting of cancer, inflammation and inflammatory diseases, tissue degeneration, periodontal disease, ophthalmological disease, dermatological disorders, fever, cardiovascular effects, haemorrhage, coagulation and acute phase response, cachexia and anorexia, acute infection, HIV infection, shock states, graft versus host reactions, autoimmune disease, reperfusion injury, meningitis and migraine.
 23. The method according to claim 21, wherein the condition is selected from the group consisting of tumour growth, angiogenesis, tumour invasion and spread, metastases, malignant ascites and malignant pleural effusion.
 24. The method according to claim 21, wherein the condition is selected from the group consisting of rheumatoid arthritis, osteoarthritis, osteoporosis, asthma, multiple sclerosis, neurodegeneration, Alzheimer's, stroke, vasculitis, Crohn's disease and ulcerative colitis.
 25. The method according to claim 21, wherein the condition is selected from the group consisting of corneal ulceration, retinopathy and surgical wound healing.
 26. The method according to claim 21, wherein the condition is selected from the group consisting of psoriasis, atopic dermatitis, chronic ulcers and epidermolysis bullosa.
 27. The method according to claim 21, wherein the condition is selected from the group consisting of periodontitis and gingivitis.
 28. The method according to claim 21, wherein the condition is selected from the group consisting of rhinitis, allergic conjunctivitis, eczema and anaphylaxis.
 29. The method according to claim 21, wherein the condition is selected from the group consisting of atherosclerosis and congestive heart failure.
 30. The compound according to claim 1, wherein R¹⁴ is C₁₋₄ alkyl optionally substituted with phthalimido.
 31. Compounds of formula (I): ##STR19## wherein: R¹ is C₁₋₆ alkyl, C₂₋₆ alkenyl, (C₁₋₆ alkyl) aryl, aryl, (C₁₋₆ alkyl) heteroaryl, heteroaryl or C₁₋₆ alkyl AR⁹ group where A is O, NR⁹ or S(O)_(m) where m=0-2, and R⁹ is H, C₁₋₄ alkyl, C₆₋₁₀ aryl, C₅₋₁₀ heteroaryl, (C₁₋₄ alkyl) C₆₋₁₀ aryl or (C₁₋₄ alkyl) C₅₋₁₀ heteroaryl, wherein if A=NR⁹ the R⁹ groups may be the same or different;R² is hydrogen or a C₁₋₆ alkyl group; R³ is a (Alk)_(n) R⁶ group where Alk is a C₁₋₆ alkyl or C₂₋₆ alkenyl group and n is zero or an integer 1; X is a group NR⁴ R⁵ where R⁴ is hydrogen or the group C₁₋₆ alkyl optionally substituted by amino (NH₂), aryl, arylamino, protected amino, di(C₁₋₆ alkyl) amino, mono(C₁₋₆ alkyl) amino, CO₂ H, protected carboxyl, carbamoyl, mono(C₁₋₆ alkyl) carbamoyl, di (C₁₋₆ alkyl) carbamoyl, and R⁵ is hydrogen or a C₁₋₆ alkyl group; --NR⁴ R⁵ may also form a ring; R⁷ is hydrogen or the group R¹⁰ CO where R¹⁰ is a group C₁₋₄ alkyl, C₁₋₄ alkylaryl, (C₁₋₄ alkyl) heteroaryl, cyclo (C₃₋₆) alkyl, (C₁₋₄ alkyl) cyclo (C₃₋₆) alkyl, C₂₋₆ alkenyl C₂₋₆ alkenylaryl; R⁸ is aryl (optionally substituted with R¹¹), heteroaryl (optionally substituted with R¹¹), (C₁₋₄ alkyl) R¹¹, (C₁₋₄ alkyl) aryl (optionally substituted with R¹¹), (C₁₋₄ alkyl) heteroaryl (optionally substituted with R¹¹), cyclo (C₃₋₆) alkyl (optionally substituted with R¹¹), cyclo(C₃₋₆) alkenyl (optionally substituted with R¹¹), (C₁₋₄ alkyl) cyclo (C₃₋₆) alkyl (optionally substituted with R¹¹), the groups: ##STR20## where p=1-2, or the group: ##STR21## where B and C may be selected from the groups O,S, C(R⁹)₂, or NR⁹ and these may be the same or different; R⁶ is an optionally substituted cyclo (C₃₋₆) alkyl, cyclo (C₃₋₆) alkenyl, C₁₋₆ alkyl, aryl, C₁₋₆ alkoxy aryl, benzyloxyaryl, heteroaryl, COR⁹, (C₁₋₃ alkyl) aryl, (C₁₋₃ alkyl) heteroaryl, alkyl-CO₂ R⁹, C₁₋₆ alkyl-NHR⁹, AR⁹, CO₂ R, CONHR, NHCOR, NHCO₂ R or NHSO₂ R, R being defined as for R¹⁰ ; R¹¹ is hydrogen or a SR⁷, COR¹³, SO₂ R⁹ (when R⁹ is not H), SO₂ N(R⁹)₂, N(R⁹)₂, NR⁹ R¹², OR⁹, COR⁹ or the groups: ##STR22## R¹² is hydrogen or a COR⁹, CO₂ R⁹, CONHR⁹ or SO₂ R⁹ (where R⁹ is not 11) group; R¹³ is a OH, OC₁₋₄ alkyl, O(C₁₋₄ alkyl) aryl, N(R⁹)₂ (in which R⁹ is the same or different), C₁₋₄ alkyl, aryl, heteroaryl, (C₁₋₄ alkyl) aryl or (C₁₋₄ alkyl) heteroaryl group;and the salts, solvates and hydrates thereof. 